The study evaluated why crop growth is inhibited after removing poultry manure stacks by analyzing soil samples from the stacking site. Soil samples found high levels of soluble salts like ammonium, potassium, and manganese in the upper soil profile at the stack center, which can create toxic conditions for germinating seeds. Over time and precipitation events, these salts are flushed from the soil and productivity returns. The passage of time is the ultimate solution, but tilling soil or adding lime before stacking can help speed remediation. Poultry manure stacks pose little risk to groundwater if sited properly but can inhibit crop growth due to soluble salt release.

1. Water Quality Impacts of Poultry Manure Headland Stacks Soluble Salt Study Paul T. Kivlin Dennis R. Frame Nutrient Management Specialist Director – Professor Nutrient and Pest Mgmt. Program UW - Discovery Farms University of Wisconsin – Extension

2. Livestock producers asked: “When a pile of manure has been in place for a period of time, why is it difficult to establish crops on the stacking site?”

3. Goal of the study Evaluate why crops do not grow for a period of time after removing a pile of manure. This objective was studied in the surface water phase of the project.

4. Goal of the study The observed inhibition of plant growth is of concern to producers and to the regulatory community. Determine if the inhibition of plant growth was also a concern for groundwater.

5. Study design To evaluate these objectives, a site that met WDNR requirements regarding soil type, slope, soil test levels and location for headland stacked poultry manure was selected.

6. Location: St. Croix County Soil: Jewett Silt Loam Slope: Two Percent Stacking Date: November, 2003

7. Methods The soil at the site was sampled before the stack was established and after the manure was removed. Soil samples were taken in the center of the stacking site where the depth of the pile was the greatest and at the edge of the stack around the entire perimeter.

8. Creating the stack

9. Methods Soil samples were analyzed for a range of constituents including: total nitrogen, nitrate, ammonium, phosphorus, potassium, manganese, and other soluble salts

10. Methods After one year the manure stack was deconstructed and the manure was applied to the surrounding cropland.

11. Stack was deconstructed and sampled

12. What’s occurring 0-36” under the headland stack?

13. Soil Sample Analysis Results Background Site Conditions Sample Depth NO3- NH4+ (inches) (ppm) (ppm) 0-6 10.4 2.6 6-12 8.7 2.0 12-24 3.8 1.6 Soil Analysis Results from Center of Former Stack Site Sample Depth NO3- NH4+ (inches) (ppm) (ppm) 0-6 31.3 717.8 6-12 44.5 676.5 12-24 34.0 93.4 24-36 3.6 49.3 Soil Analysis Results from Inside Edge of Former Stack Site Sample Depth NO3- NH4+ (inches) (ppm) (ppm) 0-6 34.3 26.4 6-12 22.6 36.2 12-24 48.5 9.0 24-36 44.5 6.1

14. Soil Sample Analysis Results Background Site Conditions Sample Depth NO3- NH4+ Soluble Salts (inches) (ppm) (ppm) (mhosx10-5/cm) 0-6 10.4 2.6 12 6-12 8.7 2.0 <10 12-24 3.8 1.6 <10 Soil Analysis Results from Center of Former Stack Site Sample Depth NO3- NH4+ Soluble Salts (inches) (ppm) (ppm) (mhosx10-5/cm) 0-6 31.3 717.8 137.3 6-12 44.5 676.5 113.3 12-24 34.0 93.4 23.0 24-36 3.6 49.3 14.0 Soil Analysis Results from Inside Edge of Former Stack Site Sample Depth NO3- NH4+ Soluble Salts (inches) (ppm) (ppm) (mhosx10-5/cm) 0-6 34.3 26.4 121.7 6-12 22.6 36.2 126.7 12-24 48.5 9.0 63.3 24-36 44.5 6.1 32.3

17. Results and Discussion Post stacking soil analysis results revealed high levels of soluble salts; primarily ammonium, potassium, and manganese, in the upper soil profile

18. Results and Discussion

19. Results and Discussion

20. Results and Discussion

21. Results and Discussion

22. Results and Discussion The presence of these salts at their elevated levels can lead to toxic conditions for germinating seeds and would largely account for the lack of plant growth on previous manure stacking sites.

23. Results and Discussion Because of the solubility of these accumulated salts, over a period of time (and a number of precipitation events), they are flushed from the soil and productivity returns.

24. Results and Discussion The high level of ammonium in the center of the stack in the upper 12 inches of the soil profile probably occurs because of the lack of oxygen and the interaction between the soil, manure and moisture moving between the stack and the soil.

25. Results and Discussion While manure stack sites have not been extensively researched, plant growth inhibition associated with heavy/repeated manure applications has been well documented and are not necessarily linked to animal species.

26. Results and Discussion Surprisingly, there was little variation in pH levels before the headland stack was established and after it was removed.

27. Remediation Recommendations The passage of time is the ultimate solution to returning soil productivity once a stack is removed, but other techniques could be utilized.

28. Remediation Recommendations Working the soil with aggressive tillage to mix the soil and release some of the nitrogen may speed up the process.

29. Remediation Recommendations Pack lime screenings or papermill sludge on the site prior to making the stack, establishing a break between the manure and soil surface. This barrier can minimize the movement of soil moisture into and out of the bottom layer of stacked manure.

32. For Additional Information http://www.uwdiscoveryfarms.org UW Discovery Farms 40195 Winsand Drive PO Box 429 Pigeon Falls, WI 54760 1-715-983-5668 jgoplin@wisc.edu or drframe@wisc.edu